Paper machinery



Juiie 10, 1958 J. BAXTER, JR

PAPER MACHINERY 5 Sheets-Sheet 2 Filed May 22, 1956 w w N a 4% mmD QQ D :@D D MR m a a a m m m m w QM H m Kw m Ow M mm June 10, 1958 .1. BAXTER, JR 2,837,977

PAPER MACHINERY Filed May 22, 1956 1 3- SheecsSheet 3 H640 1 v [I1 I: 1 '15 m EMEEEE[] 1 I W W V 106 @101 16 v J11 I I Fl G 41 AVA VA IN V EN TOR.

JOSEPH BAXTER,JR.

ATTORNEYS stat 2831977 Patented June 10, 1958 2,837,977 PAPER MACHHNERY Joseph Baxter, in, Franklin, @hio, assignor to The Black- Clawson Company, Hamilton, Shin, a corporatian of Ohio I Application May 22, 1956, Serial No. 586,462

13 Ciaims. (Cl. sis- 47 This invention relates to a rotary refiner of the Jordan type commonly used for refining of paper making stock and embodying a rotating conical plug in a complementary shell.

The invention has a primary objective the provision of a refiner of this type which will offer major practical advantages of simplicity of construction, ease of assembly and maintenance, convenience of installation, and substantial suppression of the noise of operation.

One of the specific objects of the invention is to provide a refiner of the above type wherein the main shell body is equipped at each end with a removable cover and wherein both the inlet and outlet ports are constructed in the main body itself so that one or both of the end covers may be removed for access to the interior of the body without disconnecting the piping lead ing to and from the interior of the body.

An additional object is to provide a refiner as outlined in the preceding paragraph wherein the end cover adjacent the larger end of the plug is secured to the main body by a quickly detachable connection for ease of removal whenever it is desired to change the filling and wherein also this quickly detachable connection incor porates a simple and effective sealing mechanism assuring maintained sealing during operation of the refiner.

Another object of the invention is to provide a refiner of the above type which is equipped adjacent each end thereof with a pair of inlet and outlet ports on opposite sides thereof for selective connection with the piping leading to and from the refiner and especially to provide such a refiner wherein the inlet port which is not connected with the piping will function as a trap for the accumulation of tramp metal and other hard trash material to prevent such material from entering between the refining surfaces of the plug and shell.

A further object of the invention is to provide a refiner of the above type wherein the conical shell portion of the main body is formed primarily by a wall located within the body and spaced inwardly from the outer wall of the main body in such manner as to define therewith a dead air space for mufi ling the noises created within the shell during operation of the refiner.

It is also an object of the invention to provide a rotary refiner of the Jordan type which includes end stands for the plug shaft of novel construction facilitating lubrication of the bearings for the shaft, and especially to provide such an end stand adjacent the larger end of the plug which is constructed for ready release and bodily movement with respect to the main refiner body to withdraw the plug for maintenance work on the plug or shell fillings.

Stillfurther objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the-drawings:

Fig. 1 is a view in side' elevation showing a rotary refiner constructed in accordance" with the invention;-

' Fig.2 is azplan view ofthe-refinerl of Fig.1;

Fig. 3 is an enlarged view in vertical section through the refiner of Figs. 1 and 2 as indicated by the line 3-3 of Fig. 2;

Figs. 4 and 5 are enlarged fragments of Fig. 3 illustrating details of the connections between the end covers and the main body of the refiner;

Fig. 6 is a section through the main body of the refiner taken on the line 66 of Fig. 3 and on a smaller scale;

Fig. 7 is a fragmentary section on the line 77 of Fig. 6;

Fig. 8 is a fragmentary end view of the refiner looking from right to left in Figs. 1-3 and illustrating the quickly detachable connection between the main body and the end cover adjacent the larger end of the plug;

Fig. 9 is a view taken generally 'as indicated by the line 99 of Fig. 1 and showing the refiner equipped with a trap for heavy reject material;

Fig. 10 is an enlarged view partly in side elevation and partly broken away showing features of the end stand adjacent the larger end of the plug;

Fig. 11 is a fragmentary section on the line 11-11 of Fig. 10; and

Fig. 12 is an enlarged detail section on the line 1212 of Fig. 11.

of the refiner and is supported by means of separate end stands and bearing assemblies 14 and 15 shown as having a common base 16. 0ne end of the shaft 13 is connected as by means of a coupling 17 to the drive shaft of a motor 18. The other end of the shaft is provided with an adjusting mechanism indicated generally at 20 for adjusting the axial position of the plug within the shell to control the relative spacing between the plug and shell bars 21 and 22, a suitable such adjusting mechanism being disclosed in Staege et al. Patent No. 2,666,368 issued Iannary 19, 1954 to the assignee of this application.

The main body it) is shown in detail in Figs. 3 and 6, and it includes an outer wall composed primarily of a semi-cylindrical upper portion 25 and a pair of side portions 26 and 27 extending tangentially downwardly from the upper wall portion 25 and terminating in longitudinally extending flanges 28 which may be bored and tapped as shown in Fig. 6 for attachment by bolts 29 to the base 16. At each end, however, the main body is formed with cylindrical annular flange portions 30 and 31 adjacent the smaller and larger ends of the shell 11 respectively and coaxial therewith. Below each of the cylindrical flanges 3t) and 31 is a web 32 and 33 respectively, and these webs extend across the end of the body and are shown as provided on the under edges thereof with keyways 34 for receiving locating keys 35 on the base 16.

The ends of the main body it are provided with covers 4t and it which are secured to the flanges 3t) and 3!; respectively and cooperate therewith to define an inlet chamber s4 adjacent the small end of the shell and an outlet or discharge chamber 45 adjacent the larger end of the shell. These end covers are shown as essentially dome-shaped and may be readily formed of initially identical configuration by spinning from stainless steel or other suitable corrosion resistant metal. The

"junction between the inlet end cover iii and the shaft 49 in the portions thereof extending througheach of the packing boxes.

The connection between the inlet end cover 4i) and the main body is shown in enlarged detail in Fig. 4. The cover 516' is provided with a circumferential 'flange Eli which seats on the flange EQ and is secured thereto by multiplebolts 5i, and the flange Si) is set back from the endof'the ,cover ehto provide a projecting portion of the cover which extends within the flange "313. The junction of these parts is effectively sealed with relatively low clamping" pressure by an O-ring 52 which is compressed against a chamfered portion 53 along the inner edge of the flange 3i and the cover 46 is therefore readily removable upon release of the bolts 51 to provide access to the inlet end of the body. This is especially advantageous in making it readily possible to remove and replace the wear ring 55 which is mounted on the smaller end of the shell and is subject to the abrasive action of the stock entering between the refining surfaces of the plug and shell' The small end of the plug carries'an agitator ring 56 which is also accessible when the cover 40 is removed aswell as when the plug is withdrawn from the shell. Y i

The outlet end cover 41 adjacent the larger end of f the shell is provided with a quickly releasable sealed connection to the main body in order to facilitate removal thereof Whenever it is necessary to change the filling of the plug orshell. Referring particularly to Figs. 3 and 5, the end flange. 31 on the body is formed with a circurnfer'ential groove 59 which receives one of the internal flanges ona s'plitlocking ring 60 of generally-channeled cross sectionQand the ends of this ring 66 are flanged and bolted together as indicated at 61. The end cover 1 is adapted to fit against the end face of the flange' 31 on thebody, but the outer peripheral portion of the flange 62 is notched at spaced intervals to provide a plurality of 41 is provided with a circumferential flange ring 62 which I:

circumferentially spaced lugs 63 which are adapted to fit a corresponding series of notches64 in the front flange parts. is sealed simlilarly to the other end of the body by means 0f an Q-ring 63 on a chamfered seat 69 on flange The shell 11 is forrned integrally with the outer walls of the body it) and is supported in inwardly spaced relation therewith by means of web portionslt and 71 ad jacent the opposite ends of the body. 7 Each of these web portions 70 and 71 is formed of generally volute shape such that each defines a pair of volute passages extend ing in both directions from the bottom of the body to the top thereof and leading it the top of the body into the adjacent end chamber 44 or respectively. The webs 74 and '71 thus completely surround the shell 11 adjacent the opposite ends thereof and cooperate therewith and withthe outer wall portions 25 16 to form atotally enclosed dead air space '72 surrounding the shell Thel portio n ofthe web 7 in the lower part of the body extends'tangentially out to the walls as and27 and is provided with'ports75. and76 which "thus ports to the inlet. chamber .44 for selective form :inletfl connection to an inlet conduit 77, thewalls 26 and 27 being. pro- 7.7 and the base vided with bored and tapped boss portions surrounding each of these ports as shown inFig. 6 for'receiving The stool; entering through;

a conventional pipe flange. either of these ports will therefore tend to flow tangen;

tially across the bottom of the web and then upwardly along the volute passage formed by the web into the upper part of the inlet chamber 44, from whence it will be supplied to the smaller end of the shell 11 around the entire circumference thereof. Either of the ports and '76 may be used to suit the convenience of the mill layout, and the unused port will be provided with a closure such as the door 78.

.The web 71 is similar in configuration to the web 70 andsimilarly' defines a pair of volute passageways con necting the dischargechamber 45 with a pair of ports 80 and 31 on opposite sides of the main body for selective attachment to the outlet conduit 32 as shown in Fig. 2, this port arrangement being identical with that of the ports '75 and 76. The stock entering the outlet chamber from between the working surfaces of the plug and-shell will therefore be conducted to the selected outlet port by the volute passageway with minimum hydraulic losses for efhcient operation. As in the case of the inlet ports, the'selection of the outlet port to be used depends on convenience, and the unused port -will be provided with a closure 83 which may be identical with the door 78.' v

This refiner construction provides a variety of important practical advantages. Thus as already noted, the piping leading to and from the refiner may be arranged on either side of the main body to suit the convenience of the mill, and the location of the inlet and outlet ports close to' the bottom of the'body offers a further distinct advantage. in facilitating anchoring of the pipes 'to'the floor'close to the'body in order to dampen the transmission; of'vibrations. Another significant contribution to quiet operationis made by' the construction of the body to'provide'the dead air space 72 surrounding the shell, which effectively absorbs and suppresses a substantial amount of thenoise and yibrations created by a reat nt tift fi The end cover arrangementfor the main body offers further practical advantages as well as economy of production. For example, with the covers of spun construction as described, both the inlet and outlet chambers will drain completely to the. adjacentlportsflwhenever it is desired to'-shut1 down,the' machine, and also there will be minimum tendency for deposit of fibers on the walls of either chamber. In addition, since the ports are cast in the main body, either or both of the end covers can be removed without in any way interfering with the piping connections, and the quickly detachable connection between the outlet end cover 41 and the body'.is" a further aid in the reduction of down time whenever it isnecessary to change or otherwise to service the fillingsI 1' A still further important p racti cal advant age is obtainedjfronr'thefarrahgement of a p air ofselectively usable ports at each end of the body, and particularly at the inletlend-i Ihusby reference to Fig. 6, it will be apparent that stock entering through the port 75 will first flow tangentially across the bottom of the body before it turns upwardly along the volute passage formed by the web 70. Both gravityand the flowpattern of this entering stock will therefore tend to throw; tramp metal or other reject material towards the unused port 76, and the space within the bodyqadjacent this port will tend to actas a trap for such-reject material. It will therefore be asimplematter-to remove such reject material periodicall by shutting off theincoming flow to the refiner andthen opening the closure door 78 to take out the accumulated trash. The unused ports may also-be employed toadvantage for flushing, out. the'interior of the refiner ,by;means ;of-,stearn or;freshiwater without interfering with themain piping connections i'for the stock.

Fig. 9 illustrates further means for utilizing one of the ports at the inlet end of the body for reject trapping purposes. In Fig.9, the inlet pipe'77 is connected as in Figs. 1 and 2 to theport 75, but'the port 76 is connected to a trap unit comprising an elbow 90, a first valve 91, a pipe section 92, a second valve 93 and a discharge pipe 95. In normal operation, the valve 91 will be open and the valve 93 will be closed, and heavy reject material will therefore be thrown through the elbow 90 into the pipe section 92. At intervals, this reject material is removed by shutting valve 91 and then opening valve 93, and this may be done without interference with the normal flow of stock through the refiner. Im-

proved operation is obtained by bleeding a small flow of water into the pipe section 92 just above the valve 93, as shown in Fig, 9 by the line 96 having a control valve 97.

Figs. -12 illustrate details of the end stand for the larger end of the plug which facilitates maintenance of the refiner. During operation of the unit, the pedestal 100 is rigidly secured to the base 16 by screws 101, but provision is made upon release of these screws for moving this entire assembly bodily along base 16 to the extent necessary to withdraw the plug 12 from the body for service of their respective fillings. For this purpose, the base 16 is equipped with extension means 102 such as rails secured thereto as shown in Fig. 10.

The movement of the end stand 15 is eifected by means of a pair of shafts 105 and 106 extending across the bottom of the pedestal 100 and journaled in bushings 107. Each of these shafts includes an eccentric portion 110 near each end thereof, and a ball bearing 111 is journaled on each of these eccentrics and is held in place thereon by a collar 112 or stop arm 115. Each shaft is also provided at one or both ends with a noncircular portion 116 for receiving a crank or other operating lever.

With this construction, when the refiner is in operation, the shafts 105 and 106 are turned to the positions shown in Figs. 10-12 in which the bearings 111 are out of contact with the base 16, and the pedestal 100 is screwed directly to the base. When the plug is to be withdrawn from the body, the screws 101 are removed, and the shafts 105 and 106 are rotated to shift the eccentrics thereon downwardly until the bearings 100 engage the track portions 120 of the base and then raise the pedestal free of the base. The stop arms 115 engage the adjacent flange portions 121 and 122 of the pedestal to index the shafts in the desired adjusted position-in which the eccentrics 110 have moved just past lower dead center-and then the entire unit 15 can be rolled along the base'16 and extension 102 by means of bearings 110 to the desired extent.

Fig. 10 also illustrates the convenient provisions in the pedestal 100 for lubricating the bearing assembly for the plug shaft 13. The housing 125 contains a lubricating assembly, including a pump and drive motor,

for providing a circulating oil supply to the hearing assembly by way of the oil lines 126 and 127. The housing 125 may be exchanged as a unit without interfering ing seals at the junctions between said shaft and said with operation of the refiner, by simply uncoupling the oil lines, and a similar lubricating assembly is provided in the end stand 14, as indicated by the oil line 128 in Fig. 1.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. A rotary refiner of the character described for liquid slurry stock comprising a main body having coaxial annular end portions, a frustoconical shell within and integral with said main body and of substantially smaller diameter at both ends than the adjacent end portion of said main body, a cover secured to each of said end portions ofsaid main body in overlying relation with covers.

2. A rotary refiner of the character described for liquid slurry stock comprising a main body including an outer wall having coaxial annularend portions, a frustoconical shell within and integral with said main body and of substantially smaller diameter at both ends than the adjacent end portion of said main body, integral Web means supporting said shell within said body and cooperating with both thereof to form an enclosed space between said shell and said outer wall of said body for mufiiing sound from within saidshell, :a cover secured to each of said end portion of said main body in overlying relation with the adjacent end of said shell and cooperating therewith to define end chambers for stock adjacent each end of said shell, means forming part of said main body and adjacent each end thereof defining a port connecting with the adjacent said end chamber, means for connecting inlet and outlet conduits for stock to said ports adjacent the smaller and larger ends of said shell respectively, a frustoconical plug substantially complementary to said shell, means including a shaft extending through said covers and mounted externally thereof for supporting said plug for rotation within said shell, and means forming seals at the junctions between said shaft and said covers.

3. A rotary refiner of the character described for liquid slurry stock comprising a main body having coaxial cylindrical end portions, a frustoconical shell within and integral with said main body and of substantially smaller diameter at both ends than said end portions of said shell, a generally dome-shaped cover secured to each of said end portions of said body in overlying relation with the adjacent end of said shell and cooperating therewith to define end chambers for stock adjacent each end of said shell, means forming part of said main body and adjacent each end there-of defining a port connecting with the adjacent said end chamber, means for connecting inlet and outlet conduits for stock to said ports adjacent the smaller and larger ends of said shell respectively, a frustoconical plug substantially complementary to said shell, means including a shaft extending through said covers and mounted externally thereof for supporting said plug for'rotation within said shell, and means forming seals at the junctions between said shaft and said covers.

4. A rotary refiner of the character described for liquid slurry stock comprising a main body including an outer wall having coaxial annular end portions, a frustoconical shell within and integral with said main body and of substantially smaller diameter at both ends than the adjacent end portion of said main body, a cover secured to each of said end portions of said main body in overlying relation with the adjacent end of said shell and cooperating therewith to define end chambers for stock adjacent each end of said shell, said main body including at each end thereof a portion defining a generally volute passage connecting at one end with the adjacent said end chamber and having a port at the other end thereof extending through said wall of said body, means for connecting inlet and outlet conduits for stockt-o said ports adjacent the smaller and larger ends of said body respectively, a frustoconical plug substantially complementary to said shell, and means including a shaft extending r 2 through said covers and mounted externally thereof for supporting said plug for rotation within said shell.

5. A. rotary refiner of the character described for li uid slurry stock comprising a main body having coaxial annular end portions, a frustoconical shell within and integral with said. main body and of substantially smaller diameter at both ends than the adjacent end portion of said main body, a cover secured to each of said end portions of said main body in overlying relation with the adjacent end of said shell and cooperating therewith to define end chambers for stock adjacent each end of said shell, said main body including at each end thereof a portion defining a pair of generally volute passages extending in both directions from the bottom of said body to the top thereof and leading at the top of said body into the adjacent said end chamber, means defining pair of ports on. each side of said body and adjacent the bottom thereof connecting substantially tangentially into the adjacent said volute passages, means for connecting inlet and outlet conduits for stock to a selected one of each of said pair of ports adjacent the smaller and larger end of said shell respectively, closure means for blocking the others of said ports, a frustoconical plug substantially complementary to said shell, and means including a shaft extending through said covers and mounted externally enclosed space between said shell and said outer wall :5

of said body for mufiling sound from Within said shell, a cover secured to each of said end portions of said main body in overlying. relation with the adjacent end of said shell and cooperating therewith to define end chambers for stock adjacent each end of said shell, means forming part of said main body and adjacent each end thereof defining a port connecting with the adjacent said end chamber, means for connecting inlet and outlet conduits for stock to said ports adjacent the smaller and larger ends of said shell respectively, a frustoconical plug sub- 5 stantially complementary to said shell, and means including a shaft extending through said covers and mounted externally thereof for supporting said plug for rotation within said shell.

7. A rotary refiner ot' the character described for liquid slurry stock comprisim a main body having coaxial cylindrical end portions, a frustoconical shell within and integral with said main body and of substantially smaller diameter at both ends than said end portions of said shell, integral web means supporting said shell within said body and cooperating with both thereof to form an enclosed space between said shell and said outer wall of said body for mufiiing sound from Within said shell, 9. cover secured to each of said end portions of said main body in overlying relation with the adjacent end of said shell and cooperating therewith to define end chambers for stock adjacent each end of said shell, said main body including at each end thereof a portion defining a pair of generally volute passages extending in both directions from the bottom of said body to the top thereof and leading at the top of said body into the adjacent said end chamber, means defining a pair of ports on each side of said body and adjacent the bottom thereof connecting substantially tangentially into the adjacent said volute passages, means for connecting inlet and outlet conduits for stock to a selected one of each of said pair of ports adjacent the smaller and larger end of said shell respectively, closure means for blocking the others of said ports, a frustoconical plug substantially complementary to said shell, and means including a shaft extending through said 8 covers and mounted externally thereof for supporting said plug for rotation within said shell 8-. A rotary refiner or the character described for liquid slurry stool; comprising a main body including an outer wall having coaxial annular end portions, a frustoconical s'rre'l l. within and integral with said main body and of substantially smaller diameter at both ends than the adjacent end portion of said main body, a pair of covers each proportioned to fit one of said end portions of said niai body in overlying relation with the adjacent end of said shell and cooperating therewith to' define end chambers for stock adjacent each end of said shell, means defining a pair of ports extending through said outer wall of said body and connecting with said end chamb': respectively, connecting means for connecting inlet and outlet conduits for stock to said ports adjacent the smaller and larger ends of said shell respectively, afrustoconical plug substantially complementary to said shell, means including a shaft extending through said covers and mounted externally thereof for supporting said plug for rotation within said shell, and releasable means for securing said covers directly to said body to provide for selective release and withdrawal of said covers from said body for access to the adjacent said end chamber without disconnecting said conduit connecting means.

9. A rotary refiner of the character described for liquid slurry stock comprising a main body including an outer wall having coaxial cylindrical end portions, a truste conical shell within and integral with said main body and of substantially smaller diameter at both ends than the adjacent end portion of said main body, a pair of covers each proportioned to fit one of said end portions of said main body in overlying relation with the adja cut end of said shell and cooperating therewith to define end chambers for stock adjacent each end of said shell, means defining a pair of ports extending through said outer wall of said body and connecting with said end chambers respectively, connecting means for connecting inlet and outlet conduits for stock to said ports adjacent the smaller and larger ends of said shell respectively, a frustoconical plug substantially complementary to said shell, means including a shaft extending through said covers and mounted externally thereof for supporting said plug for rotation within said shell, and releasable means for securing said covers directly to said body to provide for selective release and withdrawal of said covers from said body for access to the adjacent said end chamher without disconnecting said conduit connecting means, said releasable means adjacent said larger end of said shell including a locking ring mounted for rotational move ment on said body between locking and release positions with respect to the adjacent said cover to facilitate quick removal of said cover.

10. A rotary refiner of the character described for liquid slurry stock comprising a main body including an outer wall having coaxial annular end portions, a frustoconical shell within and integral with said main body and of substantially smaller diameter at both ends than the adjacent end portion of said main body, pair of covers each proportioned to fit one of said end portions of said main body in overlying relation with the adjacent end of said shell and cooperating therewith to define end chambers for stock adjacent each end of said shell, means defining a pair of ports extending through said outer wall of said body and connecting with said end chambers respectively, connecting means for connecting inlet and outlet conduits for stock to said ports adjacent the smaller and larger ends of said shell respectively, a frustoconical plug substantially complementary to said shell means including a shaft extending through said covers and mounted externally thereof for supporting said plug for rotution within said shell, a wear ring removably secured to the smaller end of said shell and accessible for replace ment upon removal of the adjacent said cover, and releasable means for securing said covers directly to said body to provide for selective release and withdrawal of said covers from said body for access to the adjacent said end chamber without disconnecting said conduit connecting means.

11. A rotary refiner of the character described for liquid slurry stock comprising a main body having coaxial annular end portions, a frustoconical shell within and integral with said main body and of substantially smaller diameter at both ends than the adjacent end portion of said main body, a cover secured to each of said end portions of said main body in overlying relation with the adjacent end of said shell and cooperating therewith to define end chambers for stock adjacent each end of said shell, means forming part of said main body and adjacent each end thereof defining a port connecting with the adjacent said end chamber, means for connecting inlet and outlet conduits for stock to said ports adjacent the smaller and larger ends of said shell respectively, a frustoconical plug substantially complementary to saidshell, a shaft extending through said covers and supporting said plug for rotation within said shell, a base, means securing said body to said base, end stands including bearings for rotatably supporting said shaft on said base, releasable means for securing to said base the said end stand adjacent the larger end of said plug, and means carried by said releasably secured end stand for raising said end stand with respect to said base upon release of said releasable means and for effecting free movement of said end stand along said base to withdraw said plug from within said shell.

12. A rotary refiner as defined in claim 11 wherein said last named means comprises shaft means carried by said end stand and having eccentric portions thereon, anti-friction rollers on said eccentric shaft portions,

and means journaling said shaft means in said end stand in predetermined spaced relation with said base providing for rotation of said shaft means between a position retaining said rollers raised out of contact with said base and a position wherein said rollers engage said base and support said end stand out of contact with said base for rolling movement therealong on said rollers.

13. In a rotary refiner including a conical plug supported on a shaft extending through a main body mounted on a base, the combination of an end stand for supporting the end of said shaft adjacent the larger end of said plug, releasable means for securing said end stand to said base, shaft means journaled in said end stand and having eccentric portions thereon, anti-friction rollers on said eccentric shaft portions and rotating with said shaft means to a raised position out of contact with said base, and means establishing limit positions for said shaft means sufiiciently beyond the lower dead center positions for said eccentric portions thereof to eifect raising of said end stand out of contact with said base by said rollers for rotation along said base on said rollers.

References Cited in the file of this patent UNITED STATES PATENTS 1,706,944 Wessel Mar. 26, 1929 1,814,452 Nuttall July 14, 1931 2,544,971 Wells Mar. 13, 1951 2,645,983 Roberson July 21, 1953 2,666,368 Staege et al. Jan. 19, 1954 FOREIGN PATENTS 608,115 Germany Jan. 16, 1935 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,837,977 June 10, 1958/ Joseph Baxter, Jr. 7

It is herebjr certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 1, for "Web' read body column 6, line 24-, for "portion" read portions Signed and sealed this 19th day of August 1958,

(SEAL) Attest:

KARL Ido AXLINE ROBERT C. WATSON Attesting Oflicer Commissioner of Patents 

